The invention relates to an expansible anchor made of metal for anchoring in a hole drilled in a component.
Expansible anchors of that kind are especially suitable for use in hard building materials; by screwing a nut onto the threaded shank projecting beyond the component and the article to be fixed, the expander cone integrally formed with the shank is drawn into the expansible sleeve bearing against the wall of the drilled hole. The expansible sleeve is consequently expanded and becomes wedged in the drilled hole. The expansible sleeve is braced in the drilled hole by integrally formed locking elements, which grip the wall of the drilled hole.
DE PS 41 17 238 discloses an expansible anchor of that kind having two cones over each of which is mounted an expansible sleeve. The expansible sleeve is provided with tunnel-like, convex beads projecting outwards that extend approximately as far as the centre of the expansible sleeve, and also a continuous longitudinal slit and several axially arranged incisions.
Although that known expansible anchor makes possible slip-free anchoring, it requires the use of a relatively large amount of energy to drive it in to overcome the resistance to insertion.
Studies have shown that the relatively rigid outer surface of the bead has an adverse effect on the insertion behaviour of the anchor. The reason for this is that the outer surface of the bead has two different regions: a rear region that behaves resiliently during the insertion of the anchor and a rigid front region. The rigid region of the bead presses hard and consequently creates large amounts of friction against the concrete and makes it difficult to drive the anchor into the drilled hole.